Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density.

DDT and its relatives alter the bird's calcium metabolism in a way that results in thin eggshells. Instead of eggs, heavily DDT-infested Brown Pelicans and Bald Eagles tend to find omelets in their nests, since the eggshells are unable to support the weight of the incubating bird.

Biodiversity hotspots are characterized by rich compositions of vascular plant species and high rates of endemism.

13.b) Rajaji- Hollock gibbon

14. a) Ocean-Desert-Tropical deciduous forest-tropical rain forest

15.d) Phytophagous insects

Survivorship curve

I. Humans and other large mammals; those who fit this curve produce few offspring, but provide them with good care.II. Ground squirrels, rodents, invertebrates, lizards, annual plants; this curve includes animals with a constant death rate.III. Oysters; those within this survivorship curve produce many offspring, but provide little to no care for them.